Track lighting is used in many commercial establishments to allow sources of light to be repositioned periodically to highlight different areas or subjects. It is also desirable to provide selected information in a selected area. An informative sign with internal illumination is mounted on track lighting to deliver a given message at one location. The sign may be relocated, and the message is changed in the sign to display a different message at another location. Efficiency requires that the displayed message must be readily changed by a relatively unskilled individual without the use of tools. The sign must be one which is essentially self-contained to provide the maximum efficiency and flexibility.